Cellular wireless is an increasingly popular means of personal communication in the modern world. To provide cellular wireless communication services, a wireless carrier typically operates a radio access network (RAN), which may include numerous base transceiver stations (BTSs or “base stations”) and associated network infrastructure. Each BTS radiates to define one or more wireless coverage areas such as a cell and cell sectors in which mobile stations can communicate with the BTS over an air interface. The BTS may then be coupled with other network elements (such a radio network controller and switching center), which may control aspects of the air interface (such as channel assignment and handoff between coverage areas) and other aspects of RAN operation. Further, the network infrastructure may provide connectivity with the public switched telephone network (PSTN) and may further provide connectivity with a packet-switched network such as the Internet or a private packet network. With this arrangement, a mobile station operating within coverage of a BTS may communicate through the RAN with entities on the PSTN and/or the packet-switched network, as well as with other mobile stations served by the RAN.
In practice, for instance, to place a call over the PSTN, a mobile station equipped to do so may transmit a call origination message over an air interface access channel to RAN, providing dialed digits. Upon receipt of the call origination message, the RAN may then assign an air interface traffic channel for use by mobile station to engage in the call, and RAN may set up the call over the PSTN to the called number. Similarly, when the RAN receives a request to connect a call to the mobile station, the RAN may page the mobile station over an air interface paging channel and may assign an air interface traffic channel for the call.
To engage in packet-data communication on the packet-switched network, on the other hand, the mobile station may need to acquire a radio link, a data link, and an network address (e.g., Internet Protocol (IP) address). To do so, for instance, the mobile station may transmit a packet-data origination request message over an air interface access channel to the RAN. Upon receipt of that message, the RAN may then assign an air interface traffic channel for use by the mobile station as a radio link. Further, the RAN or an associated entity may negotiate with the mobile station to establish a data link and to assign or arrange for assignment of an IP address for use by mobile station to communicate as a node on the packet-switched network.
An important feature of contemporary cellular wireless networks is an ability to locate the geographical position of a mobile station. Such a feature was initially developed to assist emergency services in locating a mobile station. However, the availability of location information to support E911 services has given rise to the development of many other location-based services as well.
For instance, given the location of a mobile station, a location-based service provider/application (e.g., a cellular wireless carrier or third party) that is in PSTN or packet-switched communication with the mobile station can provide the mobile station user with a weather or traffic report relevant to the user's location. As another example, a location-based service provider can report a list of services or establishments (e.g., restaurants, parks, theatres, etc.) in the mobile station user's vicinity. As still another example, a location-based service provider can provide a mobile station user with a map of the user's location or with directions for travel between the user's location and another location. And as yet another example, knowing that a mobile station is operating in a particular location, a location-based service provider can send the mobile station a location-based message, such as an advertisement or coupon for a nearby establishment. Other location-based services exist currently or will be developed in the future as well.
In practice, when a location-based service (LBS) application wants to determine the location of a mobile station, the application may send a location request message to the wireless carrier that serves the mobile station (or, if the LBS application is hosted by the carrier itself, then the application may send the request within the carrier's network to a designated entity or logic for handling). In response, the carrier may then engage in a process to determine where the mobile station is currently located, and the carrier may then generate a response to the location request and send the response to the LBS application.
Typically, a wireless carrier will operate a mobile location server (MLS) that is arranged to determine and report mobile station locations to requesting entities. The MLS may include a “mobile positioning center” (MPC) and a position determining entity (PDE), which may be integrated together. The MLS may function to determine the location of a given mobile station based on various factors such as (i) the identity and location of the cell/sector in which the mobile station is currently operating, (ii) satellite-based positioning information provided by the mobile station, (iii) round trip signal delay measurements, and/or (iv) signal strength measurements. Further, the carrier may operate a front end server for receiving location requests from LBS applications and forwarding those requests to the MLS.
When the MLS receives a request for the location of a particular mobile station, the MLS (e.g., MPC/PDE) may thus determine the location of the mobile station. The MLS may then return the determined location of the mobile station to the requesting entity, and the requesting entity may then report or make use of the determined location, such as to provide a location-based service.
Oftentimes to determine the location of a mobile station, a carrier's MLS will need to obtain information from the mobile station itself. This information may comprise satellite positioning data, such as GPS readings or other data, information regarding the cell/sector in which the mobile station is currently operating, and information about signals that the mobile station is receiving from various base stations, for instance. To obtain this data from the mobile station, the MLS may thus need to communicate with the mobile station.